Annual seed-propagated weed with a thin taproot, opens flowers before rain. A. arvensis was used as a medicinal plant against mental diseases.
Sessile, opposite leaves.
Cotyledons spatulate, acuminate, smooth-margined, sprinkled underneath.
Prostrate, only slightly ascending, not very ramified, square in cross-section, hairless, up to 15 cm (5.9 inch).
Round oval to broad ovate, deep green, glossy, with dark dots underneath, entire margin, nearly sessile, crosswise opposed or coroniform in groups of three.